If you're looking for the cheapest flights during the Christmas season, it's best to book your tickets as early as possible. Prices tend to rise as the holidays approach due to increased demand. Try to plan your travel several months in advance to secure the best rates. Additionally, consider traveling on less popular travel dates, such as on Christmas Day itself or the days immediately following Christmas. These dates often have lower fares as airlines try to fill empty seats. It's also worth checking budget airlines and comparison websites for additional discounts and deals.